Swiss research shows that tannin-containing sainfoin (Onobrychis viciifolia) and acacia extract (Acacia mearnsii) reduce nitrogen excretion via the urine and the release of ammonia from the liquid manure. Condensed tannins bind to the crude protein in the feed and slow down its rate of breakdown in the rumen, shifting the route of N excretion from urine to faeces and reducing the NH3-releasing potential of the excretions. The feeding of sainfoin silage reduced the digestibility of organic matter compared to the feeding of grass and clover silage. Acacia extract reduced the feed intake and the digestibility of the organic matter in all investigated silage types and also the milk yield. However: the feeding of acacia extract reduced the release of ammonia from the liquid manure by up to 37 percent.